Granted Patent
Utility
US 4,233,392 · App. 06/031,977
Light-sensitive material for tanning development comprising pretreated carbon
Inventor:
Horst Friedel
Patented Case
View Patent ↗
Granted: Nov 11, 1980
Filed: Apr 20, 1979
Inventor
Horst Friedel
Assignee (at issue)
E.I. DU PONT DE NEMOURS AND COMPANY
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.